Electrical submersible pumps (ESP) are commonly used in wells to pump well fluid being produced by the well. A typical ESP includes a pump driven by an electrical motor. The pump is often a centrifugal pump, but it could be other types.
It is also known to employ an ESP on or near a sea floor to boost the pressure of well fluid flowing from a subsea well. Normally, the ESP is located in a subsea conduit, such as a flowline canister. The conduit has an inlet near one end and an outlet at the opposite end. A power cable or motor lead extends into the conduit and connects to the motor. The motor lead and its electrical connection to the motor are exposed to the well fluid flowing into the conduit. Failures of the electrical connection can occur due to the immersion in the well fluid.
Sensor units are optionally employed with ESPs, particularly with ESPs submersed in wells. Normally, the sensor unit secures to a lower end of the motor. The sensor unit has sensors that sense various parameters of the motor and/or the well fluid. A sensor wire or wires may extend from the motor into the sensor unit for powering the sensors and transmitting signals. The sensor wire may connect to a null point in the windings of the motor to convey the signal over the power cable.